Contents Introduction Electric Wheel Chair (EWC) Mechanical structure EWC Power System EWC Control System Future Improvement

Introduction “Give me a wheelchair that is light and compact, that fits in a small plane when I need to fly out in the wet season. Make sure it’s comfortable, does not give me pressure sores, to make me look like a cripple straight out of hospital. It has to be easy to push because I want to get out, go crabbing in the boat and go fishing on the beach.” (Hales S 2001) This quotation describes the needs of a wheelchair user in the community. A people with special needs is( 3_4)% of the total population. Electric wheel chairs (EWC) provide functional mobility for people with both lower and upper extremity impairments. EWC are becoming increasingly important as more users transition from manual mobility to electric powered mobility specially in Palestine which has high percent of disabled people due to many reasons

Our Contribution Our contribution was to install all the components in the project and do tests to get our Goal . To find the best solution for each situation individually. So, we will save power and money. And it will be a very good business here in Palestine. We will startup so soon

ELECTRIC WHEELCHAIR

Mechanical Structure Satisfies the international standards Satisfies the main target of this project

EWC Control System Microcontroller Drive Power Switches Heat Sinking Optical Encoder Joystick

Microcontroller Arduino

Microcontroller Arduino

Drive Why Drive Circuit? H-Bridge Isolation between low voltage(Microcontroller) and high voltage. Regulating the direction and speed of the motor. H-Bridge H-bridge is an electronic circuit, containing four switching elements, which enables a voltage to be applied across a load in either direction, in an H like configuration. This circuit allows DC Motor to run clockwise or anti- clockwise.

Drive Components of H-Bridge Power switches Catch diode

Drive Four Quadrant operations

Drive 4-Q Current Paths in H-Bridge

Drive Regenerative braking Whenever the back-EMF is greater than this voltage, you get regenerative braking.  Dynamic braking

Drive Pulse width modulation (PWM) The presence of PWM technique: Control Motor Speed Soft Starting Overcome DeadBand Region

Drive Circuit

Isolator

Power Switches Power MOSFETs Gate Frequency Gate Driver Thermal Problem & voltage drop

Power Switches Gate Driver Power MOSFETs and IGBTs are simply voltage driven switches, because their isolated gate behaves like a capacitor. In order for the MOSFET to conduct, two requirements must be met: The MOSFET should have a reference ground The voltage between the gate and the source should be between 5V and 20V.

Heat Sinking Thermal power : Heat sinks are rated by P = I * (I * R) = I2 * R Where R: Junction Resistor Heat sinks are rated by their thermal resistance  (Rth) in °C/W. Rth = (Tmax - Tair) / P  Tmax: Max. allowed Element Temperature Tair: surrounding air Rth chosen should be less than calculated.

Optical Encoder To measure the speed. Just one photo detector required. To measure the speed and the direction two photo detector with 90 degree phase shift required.

Joystick The joystick can move in two dimensions (X and Y ). Variable Resistors occur variable voltages(potentiometer)

Programming void setup() { // put your setup code here, to run once: Serial.begin( 9600 ); pinMode( A0,INPUT ); pinMode( A1,INPUT ); pinMode( 2,INPUT );//right enoder pinMode( 12,INPUT );//left enoder pinMode( 5,OUTPUT ); pinMode( 6,OUTPUT ); pinMode( 3,OUTPUT ); pinMode( 9,OUTPUT ); pinMode( 7,OUTPUT ); pinMode( 8,OUTPUT ); } void loop() { getMotor1Speed(); getMotor2Speed(); // put your main code here, to run repeatedly: getJoystick(); if(SPD <0 ){ SPD = SPD*-1; } // forworad or backword fun1(); stopMotor(); analogWrite(8,0); analogWrite(7,0); }

Future Work

Questions?

Thank You 